The iPad 10.9" Wallpaper size (1640×2360px)
1640x2360 pixels is the native portrait resolution of the 10.9-inch iPad, the standard 10th-generation model, using a roughly 41:59 Liquid Retina display. A wallpaper at this exact size fills the panel edge to edge with no upscaling, so it stays crisp on the everyday iPad's bright screen across both the Home Screen and lock screen.
The 10.9-inch iPad shares this resolution with the iPad Air, and like every iPad it rotates, so the wallpaper must read well in both portrait and landscape. This is why phone and desktop wallpapers look wrong on it; resizing to a native 1640x2360 gives iPadOS exactly the portrait canvas it needs while keeping your composition undistorted and correctly proportioned.
Since the screen is large and Retina-sharp, use a decent high-resolution source at or above 1640x2360 so the image does not soften when scaled to the tablet. Plan for the interface: the lock screen places a large clock in the upper-middle, and the Home Screen fills the display with an app-icon grid, the dock, and widgets. Keep the focal point centered so it survives rotation and stays visible behind the icons, treating the edges as areas that may be partly covered. This tool resizes entirely in your browser, so your file is never uploaded, it is free, and your original quality is preserved while the image is fit to the 41:59 frame. Apple can change specs, so verify before exporting.